﻿using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Imaging;
using System.Linq;
using System.Text;
using System.Web;
using System.Web.SessionState;

namespace publish_test
{
    /// <summary>
    /// validatecode 的摘要说明
    /// </summary>
    public class validatecode : IHttpHandler, IRequiresSessionState
    {

        public void ProcessRequest(HttpContext context)
        {
            context.Response.ContentType = "image/gif";
            using (Bitmap m = new Bitmap(200, 60))
            {
                using (Graphics g = Graphics.FromImage(m))
                {
                    g.FillRectangle(Brushes.Red, new Rectangle(0, 0, 200, 60));
                    Random r = new Random();
                    string letters = "ABCDEFGHIJKLMNPQRSTUVWXYZ";
                    string letter;
                    Font font = new Font(FontFamily.GenericSerif, 48, FontStyle.Bold, GraphicsUnit.Pixel);
                    StringBuilder s = new StringBuilder();
                    //添加随机的五个字母        
                    for (int x = 0; x < 5; x++)
                    {
                        letter = letters.Substring(r.Next(0, letters.Length - 1), 1);
                        s.Append(letter);
                        g.DrawString(letter, font, new SolidBrush(Color.Black), x * 38, r.Next(0, 15));
                    }
                    //混淆背景        
                    Pen linePen = new Pen(new SolidBrush(Color.Black), 2);
                    for (int x = 0; x < 6; x++)
                        g.DrawLine(linePen, new Point(r.Next(0, 199), r.Next(0, 59)),
                            new Point(r.Next(0, 199), r.Next(0, 59)));
                    //将图片保存到输出流中              
                    m.Save(context.Response.OutputStream, ImageFormat.Gif);
                    context.Session["CheckCode"] = s.ToString();
                    //如果没有实现IRequiresSessionState，则这里会出错，也无法生成图片         
                    context.Response.End();
                }
            }
        }

        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }
}